Research on the Vehicle-induced Dynamic Response of Close-attached Underpass with Local Void Above Ceiling
To investigate the relationship between void defects and vehicle-induced dynamic response,on-site testing was performed in this study and a dynamic numerical model was established based on a project in which the Nijiaqiao Station of Chengdu Metro Line 8 crossed the existing station with zero clearance.The influence law of void defects between the underpass roof and zero-clearance station on the vehicle-induced vibration response of the underpass was analyzed.The results show that the dynamic response of the underpass caused by the train dynamic load is mainly influenced by the relative position between the structure and the vibration source and the constraint state.The peak value of the vertical acceleration of the underpass indicates that the top plate is larger than the bottom plate.Owing to the constraint of the side wall,the midspan of the ceiling is larger than that of the side part;however,there is little difference between the midspan and the side part when it is far from the vibration source.Meanwhile,the lateral acceleration indicates that the middle wall is larger than the side part,which is constrained by the surroundings.The local voids of the close-fitting structure are equivalent to weakening the constraint and reducing the net contact area of the solid medium with strong vibration transmission,which leads to an intensified vibration response of the underpass structure.Under the calculation conditions in this study,the void ratio of 5％-30％was considered and found to have little effect on the frequency response curve and time history curve of the underpass,but shows positive correlation with the acceleration and amplitude.In addition,the relative position between the void area and the vibration source significantly influences the structural vibration response.When the void area overlaps the vibration source(i.e.,a void was present under the vibration source),the structural vibration response under the overlapping area suddenly increases.
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维普
